Pneumatic hammer.



Patented Jan. 5,1909.

I 2 SHEETS-SHBET 1.

VIII

PNEUMATIG HAMMER.

APPLICATION FILED JAN. 7, 1908.

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THE NORRIS PETERS cm. wAsmNci'oN. 0. cf

-H. B. STOCK-S8 J. R. WEBB. JR.

PNEUMATIC HAMMER. APPLICATION FILED JAN. '7, 1908.

Pate ted Jan. 5, 1909.

1H: uomus PETERS cc:, WASHINGYON. 0. c4

UNITED STATES PATENT OFFICE.

HARRY BENWELL STOCKS, OF DIDSBURY, MANCHESTER, AND JOHN RAOKER WEBB, IR, OF

EAST CLIFFE, DOVER, ENGLAND, ASSIGNORS TO THE OLIMAX PATENTS LIMITED, OF MAN- CHESTER, ENGLAND.

PNEUMATIC HAMMER.

Patented Jan. 5, 1909.

Serial No. 409,700.

To all whom it may concern.

Be it known that we, HARRY BENWELL Srooxs and JOHN RACKER WEBB, Jr., subjects of Great Britain, residing, respectively, at 107 Barlow Moor road, Didsbury, Manchester, in the county of Lancaster, England, engineer, and 36% Liverpool Lawn, East Clifl'e, Dover, in the county of Kent, England, engineer, have invented new and useful Improvements in or Relating to Pneumatic Hammers and Similar Fluid-Pressure-Operated Tools and Machines, of which the following is a specification.

Our invention relates to pneumatic hammers and like fluid pressure operated machines and tools inwhich a piston is reciprocated to and fro as is well understood, and refers chiefly to a novel means for effecting the automatic reci rocating movement of the distribution va ve used in such tools.

Under our invention we employ a distribution valve having two differential pressure areas, the smaller one of which is loaded constantly with air under pressure. The larger area is intermittently acted upon by air under pressure, and for this intermittent su ply we utilize the compressed air admitted behind the hammer piston for the blow stroke to act intermittently upon the larger area of the valve. This is known in the art but the novel feature of our invention consists in means whereby the distribution valve itself is adapted to cut off the admission of such compressed air to the larger area of the valve when the valve has been moved over, and prevent the admitted air from falling in pressure until the valve is to be moved forward again. This renders the valve certain in its action.

The pneumatic hammer forming the sub- 'ect of our invention consists of a long stroke and tool or hammer suitable as a riveting tool, in which the novel valve operating means are used, the tool being adapted to be actuated by two independent continuous streams of compressed air, one under high pressure for the blow stroke and the other under low pressure for the return stroke, the compressed air being obtained from a suitable reservoir or reservoirs.

In the accompanying drawings, to which we will now refer, Figure 1 shows a sectional elevation of the long stroke pneumatic hammer made in accordance with our invention. Fig. 2 is a detail view. Fig. 3

is'a sectional plan thereof. Fig. 4 is a sectional plan on the line AB Fig. 1. Fig. 5 is a separate view of the distribution valve.

The tool consists of a cylinder (1 in which slides snugly a cylindrical piston b. The front end of the cylinder 0, is adapted to carry a suitable riveting or other tool 0 shown separately in Fig. 2. The rear of the cylinder a is closed with a plate d bored with ports or holes as will be explained, and abutting against the plate (2 is a valve box 6 contained within the boss f of a handle 9, the parts being assembled by means of a nut 7L engaging with a screw thread formed in the end of the boss of the handle, the nut abutting against a shoulder a formed on the end of the cylinder a. The abutting surfaces of the end of the valve box e and the handle 9 of the tool are recessed to form annular grooves ij. The groove 4, contains constantly air under high pressure and the groove j air under low pressure, when the hammer is at work. The pressure fluid is conducted to the tool from a reservoir or reservoirs by means of two tubes connected respectively at k m, the admission of air to the tool being governed by a double valve n 0 mounted on a spindle p. Valve seatings for the valves n 0 are provided in a conical casing p. The valve spindle p is operated by a trigger g pivoted at g in the handle, the end g of which is in contact with and operates an auxiliary trigger T which bears against a piston s on the valve spindle the piston 8 being slidable in a cylindrica chamber 8 in the casing 12. Air under low pressure is conducted from the reservoir by the air tube along the passage 25 to the chamber 8 in front of the piston 8 (see Figs. 1 and 4). Air under high pressure is also conducted by the other air tube from the reservoir to the passage it along the port a to the chamber n in front of the valve n, (see Figs. 1 and 4). To start the tool the valve s indle is actuated by the trigger g and thrusts t e valves n 0 off their seats and permits air under low pressure to pass from the chamber 8 up a port 4) (Fig. 4) and from thence to the port 1) and to the annular groove The air under high pressure passes from the chamber a through the port to to the annular groove 41. The valves n 0 are normally kept on their seats by the spring n and the air under high pressure in the chamber n.

The distribution valve 00 is free to slide in the valve box 6 and is formed in two diameters with an annular groove 00 in the larger diameter and another groove 9: in this part, to conduct exhaust air pressure by means of holes a5 to a hollow center 90 formed in the valve and from thence by a passa e y in the handle to atmosphere. The sma ler diameter of the valve :0 at the rear is also formed with annular recess 90 The smaller area s of the distributing valve r is constantly loaded with air under pressure, preferably high pressure, from the annular recess '5 along the ports 2 in the valve box 6 forcing the valve :1: forward in the position shown in Fig. 1, at the times when the hammer piston is at the end or attaining the end of its inward or return stroke. In this rearward position of the piston b and when the distribution valve 0:, is in the position shown in Fig. 1, air under high pressure is conducted from the groove 2 through the annular recess 3 to the groove 4 and from the annular groove 4 through a port or ports 6 in the valve box and coinciding holes 7 in the plate (1 to the rear of the piston 7) driving the piston forward, while air ressure in front of the piston I) is exhausted by a port or ports 8 the rear end of which is uncovered by the distribution valve 02 to allow the air to pass through the exhaust passage y to atmosphere.

When the hammer piston has nearly completed its blow stroke, as shown in Fig. 1, the air pressure used for the blow stroke is conducted by a port 9, then opened by the hammer piston, to the annular groove 90 in the larger diameter of the valve 00 and from thence by an independent port 10 to the larger diameter 11 of the distribution valve 20 and also to a port 12 so that the distribution valve 90 is forced backwards against the constant pressure on its smaller area 8 into the position shown in Fig. 3. This opens the rear of the cylinder a to exhaust through the hole 7 in the plate (1 the port 6 in the valve box 6 and auxiliary groove 00 in the larger diameter of the valve, and the holes 95 leading to the hollow center a; of the valve, and so to atmosphere by the passage y. Air under low pressure is conducted from the annular recess j along the port 13 to the annular recess 90 in the rear or smaller diameter of the valve, along the port or ports 8 to the front of the hammer piston I) thus returning the piston in the cylinder as will be obvious from an inspection of Fig. 3. By the rearward movement of the distributing valve as the annular groove :0 is no longer coincident with the port 9 leading to the cylinder behind the piston, so that the air admitted in front of the valve 0/; is trapped and cannot exhaust, although the rear of the cylinder and the port 9 are open to exhaust.

To prevent the premature forward movement of the distributing valve 9: due to ossible leakage of the air trapped in front o the valve :20 may be dis ensed with.

valve 0: the air acting on the larger area 11 of the valve is, or may be, reinforced by air under high pressure from the port 2 by means of a port 13 and restricted outlet thereof 14. If not considered necessary or desirable the port 13 conducting air under high pressure to reinforce the air trapped in front of the larger pressure area 11 of the distributing Before the piston has reached t 1e end of its return stroke the port 12 is uncovered by the front end of the'piston allowing the air trapped in front of the larger pressure area 11 of the valve is to exhaust into the front of the cylinder and to atmosphere through the hole 14. The pressure against thelarger area 1 1 is thus so greatly reduced that the valve 0: can be moved for ward by the air pressure acting constantly on the small area 8 of the valve and the cycle of operations is repeated. It will be understood that the various ports in the cylinder and valve box used for conducting and exhausting pressure fluid may be repeated as often as necessary.

It will be obvious from the foregoing that any skilled mechanic could adapt our invention to the various types of hammers or tools containing a piston reciprocated by compressed air.

The high ressure air used for the blow stroke may e of any desired pressure and the low pressure for the return stroke may be such as will be sufficient only to promptly return the piston in the cylinder, thus obviating shock or jar on the return stroke.

We declare that what We claim is:

1. A pneumatic hammer comprising a cylinder, a tool carried thereby, a piston slidable in said cylinder, means for supplying two continuous streams. of air to said hammer, one under high pressure for the blow stroke and one under low pressure for the return stroke, a valve box, a distribution valve slidable therein and formed with two unequal pressure areas, means for conducting one stream of air constantly against the smaller area when the hammer is at work to move the valve in a forward direction, means for conducting the high pressure stream of air behind the piston for the blow stroke, exhaust means in front of the piston,"

means controlled by the piston and the. distribution valve for conducting the high pressure air from the cylinder behind the piston to the larger area of the distribution valve to force the valve to the rear so as to admit the air under low pressure in front of the piston for the return stroke and exhaust the air behind the piston, means governed by the distribution valve to cut off and trap the air admitted to the larger area of the distribution valve, and exhaustmeans operated by the piston on its return stroke for exhausting the high pressure air. acting on the larger area of the distribution valve so as to permit the air pressure acting constantly on the smaller area of the valve to again move the valve forward.

2. A pneumatic hammer comprising a cylinder, a tool carried thereby, a piston slidable in said cylinder, means for supplying two continuous streams of air to said hammer, one under high pressure for the blow stroke and one under low pressure for the return stroke, a valve box, a distribution valve slidable therein and formed With two unequal pressure areas, means for conducting one stream of air constantly against the smaller area when the hammer is at work to move the valve in a forward direction, means for conducting the high pressure stream of air behind the piston for the blow stroke, exhaust means in front of the piston, means controlled by the piston and the distribution valve for conducting the high pressure air from the cylinder behind the piston to the larger area of the distribution valve to force the valve to the rear so as to admit the air under low pressure in front of the piston for the return stroke and exhaust .the air behind the piston, means governed by the distribution valve to cut off and trap the air admitted to the larger area of the distribution valve, means for reinforcing such pressure on the larger area, and exhaust means operated by the piston on its return stroke for exhausting the high pressure air acting on the larger area of the distribution valve so as to permit the air pressure acting constantly on the smaller area of the valve to again move the valve forward.

3. In a pneumatic hammer the combination of the valve operating means comprising a distribution valve having differential pressure areas, means for constantly supplying air under pressure against the smaller area to move the valve in one direction, means for intermittingly conducting high pressure air admitted to the cylinder behind the piston for the blow stroke against the larger area to move the valve in the opposite direction, and means governed by the valve for cutting off and for trapping said air until the valve is to be moved forward again by the constant air pressure on its smaller area.

4. In a pneumatic hammer the combination of the valve, operating means comprising a distribution valve having differential pressure areas, means for constantly supplying air under pressure against the smaller area to move the valve in one direction ,means for intermittingly conducting high pressure air admitted to the cylinder behind the piston for the blow stroke against the larger area to move the valve in the opposite direction, means for reinforcing such pressure, and means governed by the valve for cutting off and for trapping said air until the valve is to be moved forward again by the constant air pressure on its smaller area.

In testimony whereof we have signed our names to this specification in the presence of two subscribing witnesses.

HARRY BENWELL STOCKS. JOHN RAOKER WEBB, JUNIOR. Witnesses:

ALFRED YATES, NORMAN KIERNAN. 

